In the specific technical field, there is a known way of providing pivotable spectacle sides by means of respective eyelet-shaped formations, fixed to the sides and to the lugs of the frames, in which are engaged screws or threaded pins forming hinge pins for the pivotable connection of the sides.
In these solutions, a first problem is posed by the undesired slackening of the screw or threaded pin, making it necessary to carry out periodic tightening, thus creating difficulties for the user who is generally not equipped with suitable tools, especially in the case of hinge devices whose sizes and overall dimensions are extremely small. The spontaneous unscrewing of the hinge screw is typically caused by the cyclic rotation, with mutual contact, of the hinge elements (the male and female parts) pivoting around the screw or hinge pin.
Another limitation that may be encountered in known solutions is that created by the phenomenon of “seizing” which occurs between the male and female parts of the hinge. In fact, the continual sliding between the surfaces of these parts facing one another and in mutual contact, the parts being typically made of the same material, may cause the hinge to jam after a certain number of rotation cycles.
Yet another limitation is that which relates to the loss over time of the frictional effect initially introduced between the hinge elements. In fact, with use, the mutual sliding contact of the hinge elements progressively increases the play in the coupling, which tends to limit the frictional effect, that is to say the resistance to rotation between the male and female parts of the hinge, resulting in the loss of this characteristic.